Mobil 1

elippse · #1 09-04-2010, 06:48 PM

I've been using Mobil 1 in my cars since the late '70s; I still have a copy of April 1976 Popular Science that addresses synthetic oil. I had a '76 Rabbit that I had used Mobil 1 in since 2000 mi. I changed its oil every 100,000 miles and added a quart every 27,000 miles. It had the head gasket fail at 198,000 miles, and the hone marks were still in the cylinder and there was NO ridge at the top of the cylinder; nein, nichts, nada. My question for those with some expertise with oils is if I mixed Mobil 1 on a 1-for-2 or 1-for-3 ratio with my Aeroshell 15-50 semi-synthetic, would that create a problem? Opinions, please!

Geico266 · #2 09-04-2010, 06:59 PM

Since Shell 15-40 is semi synthetic why bother?

If you run any 100ll the lead will be a problem with full Mobil 1.

mikegraycmg · #3 09-04-2010, 06:59 PM

This doesn't rise to the level of an opinion, because I really don't know -- it's just a hunch. I wouldn't mix synthetic oils with anything else. I suspect it won't work very well. I am using Phillips 20W-50 XC for that very reason (Aeroshell multi-viscosity oils contain synthetic elements). I suspect that the loose tolerances in airplane engines mean that synthetic oils don't work as well -- they are too slippery/

Guy Prevost · #4 09-04-2010, 07:12 PM

Exxon & Shell moved away from fully synthetic aviation oils because they were causing engine problems. They both now offer semi-synthetic blends. I wouldn't mess with the ratio they've worked out--it is based on experience. Also, there is no guarantee that the Mobil 1 will actually mix with your Aeroshell.

Just an opinion, worth what you paid for it....

Guy

jimrobmg · #5 09-04-2010, 07:27 PM

Mobil 1 doesn't have (I belive) Zinc. Found out the hard way using it in British cars, It prematurely wore the lifters. Zinc gives somekind of lubrication to older technology engines.

jlk · #6 09-04-2010, 07:35 PM

My understanding (I was actually reading about synthetics this afternoon for my Lotus) is that all the synthetics now blend fine with conventional oils. There used to be some additives in the synthetics that did not play well with regular oil. None of those additives are used any more. I would not mix my own blend of oil, but if you are running the semi synthetics you can add a quart of regular oil to top off if you run low.

Kyle Boatright · #7 09-04-2010, 07:51 PM

Pure synthetics don't suspend lead particles very effectively. Which means serious sludge accumulates in the engine. That was the issue which caused the demise of Mobile 1 aviation oil.

Mobile ended up tearing down/rebuilding/replacing quite a few engines over that one.

Aeroshell 15-50 and Exxon Elite 20-50 both contain synthetic stock, but there is sufficient non-synthetic to suspend lead particles. I'd bet those companies properly researched the ratio of synthetic vs semi-synthetic bases to create high performance oils that can handle the lead.

LarryT · #8 09-04-2010, 10:46 PM

Quote:

Originally Posted by Kyle Boatright

Pure synthetics don't suspend lead particles very effectively. Which means serious sludge accumulates in the engine. That was the issue which caused the demise of Mobile 1 aviation oil.

Mobile ended up tearing down/rebuilding/replacing quite a few engines over that one.

Aeroshell 15-50 and Exxon Elite 20-50 both contain synthetic stock, but there is sufficient non-synthetic to suspend lead particles. I'd bet those companies properly researched the ratio of synthetic vs semi-synthetic bases to create high performance oils that can handle the lead.

Paul - Kyle has the correct answer. Exxon originally marketed a fully synthetic aircraft oil "Mobil 1" that did not scavenge lead. The lead sludge plugged up oil pick-up screens causing starvation and loss of oil pressure. After paying for lots of repairs,they laid low for a few years, then brought out their semi-synthetic oil labeled "Exxon" (company name) rather than "Mobil 1" (trademark). Ben Visser, former AeroShell "Oil Guru" published several articles about the the lead scavenging issues - you might try googling his name and see if they come up. I have a lot of respect for the R & D people at Exxon. Mobil 1 aviation oil is the only one I can recall on which they stubbed their collective toes.

BTW,I run Mobil 1 in all my cars, which run on unleaded gas, of course

LarryT

MrNomad · #9 09-05-2010, 09:11 AM

Quote:

Originally Posted by Kyle Boatright

Aeroshell 15-50 and Exxon Elite 20-50 both contain synthetic stock, but there is sufficient non-synthetic to suspend lead particles.

Kyle, When I bought my Superior engine in 2007, Exxon had a promo on their Elite for $2.50 a quart & I bought a bunch. Is it safe to assume that the Elite sold in 2007 has the composition "there is sufficient non-synthetic to suspend lead particles" you mentioned?

It's been 230 hours and all oil samples come back great!

Barry

Kyle Boatright · #10 09-05-2010, 09:19 AM

Quote:

Originally Posted by MrNomad

Kyle, When I bought my Superior engine in 2007, Exxon had a promo on their Elite for $2.50 a quart & I bought a bunch. Is it safe to assume that the Elite sold in 2007 has the composition "there is sufficient non-synthetic to suspend lead particles" you mentioned?

It's been 230 hours and all oil samples come back great!

Barry

I think everyone had learned the lessons from Mobile 1 by that time, so yes, I would assume Exxon Elite is properly engineered.